Intrusive discs disturb symmetry of weak saddle strikes

In this undated Lincoln cent a normal first strike was followed by a saddle (tandem) strike. The smaller of the two off-center strikes is weak, while the other is much stronger due to the presence of an underlying planchet. Images by Mike Diamond.

This Lincoln cent planchet received a weak first strike as it sat within the collar. It was followed by two overlapping saddle strikes. An intrusive planchet increased the effective striking pressure at one pole. Images by Mike Diamond.

This undated Roosevelt dime may or may not be a saddle strike. One pole — die-struck on both faces — is very weakly struck. The opposite pole shows a much stronger strike owing to the presence of an underlying coin. Images by Mike Diamond.

Earlier presses used at U.S. Mint facilities, mainly before 2002,
often employed die pairs arranged in one or two closely spaced
couplets, at least when striking cents through dimes.

The gap separating a couplet was so narrow that a planchet or coin
could straddle that gap and be struck simultaneously by both die
pairs. These tandem strikes are called saddle strikes, reflecting the
shape of the hump that often develops in the unstruck interval between
the off-center strikes.

In a dual or quad press, all the dies are linked to a common
mechanism and thus operate in synchrony. If a malfunction interferes
with normal die approximation, all the connected die pairs would be
expected to produce equally weak strikes. Most of the time, however, a
low-pressure saddle strike will show asymmetrical strength because the
excess space in one striking chamber is taken up by an intrusive
planchet or coin.

Illustrating this kind of asymmetry is a Lincoln cent in which a
normal first strike was followed by a saddle strike. We can tell this
is a saddle strike by the head-to-head orientation of the two
off-center obverse designs, which make their closest approach at the
1:00 position typical of cents minted between 1980 and 2001. The
minimum separation between the two off-center strikes also falls
within the normal range.

The smaller of the two off-center strikes is die-struck on both
faces and is weak. The larger, stronger strike is uniface (struck
against an underlying planchet). The intrusive planchet took up the
excess space between the dies, boosting the striking pressure in this area.

Since the first (centered) strike was of normal strength, it would
appear that something interfered with normal die approximation after
that strike was delivered.

Our second Lincoln cent, carrying the partial date 20__, shows
four visible strikes, with a fifth strike implied by the tandem nature
of the off-center strikes. Here a very weak but perfectly centered
first strike was followed by two closely overlapping saddle strikes.
As with our first example, the off-center strikes show a head-to-head
orientation at the 1:00 position; the minimum separation between the
first pair of tandem strikes is 12.01 millimeters. The weakness in the
initial strike shows that the minimum die clearance was already excessive.

Two small off-center strikes — the first clearly die-struck on
both faces — overlap Lincoln’s shoulder. Both strikes are quite weak.
At the opposite pole we see a single visible off-center uniface strike
that is quite strong. Again, an underlying planchet took up the excess
space between the dies, increasing the effective striking pressure.

Our final example comes from Alexander Ness. I’m not entirely sure
this undated Roosevelt dime is a saddle strike, as the closest point
between the two off-center obverse designs is at 12:00 rather than the
11:00 position typically seen in this denomination. Furthermore, the
minimum separation between the two strikes seems intermediate between
the very narrow gap that prevailed before the late 1970s and the more
generous separation that prevailed afterward.

What we can establish is that one pole displays a very weak strike
that is die-struck on both faces. Here the obverse design is limited
to Roosevelt’s brow and eye atop the planchet’s proto-rim and a weak
outline of the rest of his head within the body of the planchet. The
reverse design shows up only on the proto-rim where we see the PLU of PLURIBUS.

The off-center strike at the opposite pole is considerably
stronger. The obverse face is die-struck and shows the top of
Roosevelt’s head and the Y of LIBERTY. The reverse face shows a mirror
brockage of the same portion of the obverse design. It would appear
that an underlying coin took up the excess space between the dies. The
outer edge of the struck tongue of metal is flattened and serrated.
It’s a chain strike that carries the impression of the reeding of
another dime that lay adjacent to this planchet when the off-center
strike was delivered.

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The Commission of Fine Artsâ recommendation for the Proof 2014 American Eagle platinum coin, left, brought outrage and derision at the Citizens Coinage Advisory Committee meeting. The CCAC recommended the design to the right.

The Commission of Fine Artsâ recommendation for the Proof 2014 American Eagle platinum coin, left, brought outrage and derision at the Citizens Coinage Advisory Committee meeting. The CCAC recommended the design to the right.

The Commission of Fine Artsâ recommendation for the Proof 2014 American Eagle platinum coin, left, brought outrage and derision at the Citizens Coinage Advisory Committee meeting. The CCAC recommended the design to the right.

The Commission of Fine Artsâ recommendation for the Proof 2014 American Eagle platinum coin, left, brought outrage and derision at the Citizens Coinage Advisory Committee meeting. The CCAC recommended the design to the right.

The Commission of Fine Artsâ recommendation for the Proof 2014 American Eagle platinum coin, left, brought outrage and derision at the Citizens Coinage Advisory Committee meeting. The CCAC recommended the design to the right.